Inorganic reinforcing agents are added to coatings with the aim of improving various properties including mechanical properties such as abrasion, scratch and impact resistance as well as adhesion. Optical properties, such as gloss, can also be modified by the addition of certain inorganic materials. The main materials used in order to modify the properties of coatings are silica (fumed or crystalline), aluminum oxide, calcium carbonate and titanium dioxide. Some of these materials are not easily dispersible in aqueous mediums and they have a certain level of toxicity.